Method of and means for circulating a heat-transferring liquid in a closed system



April 3, 1956 w. BENDER 2,740,588

METHOD OF AND MEANS FOR CIRCULATING A HEAT-TRANSFERRING LIQUID IN ACLOSED SYSTEM Filed March 1, 1952 I m emon' Wmu BEHDER METHOD F ANDMEANS FOR CIRCULATING A HEAT-TRANSFERRING LIQUID IN vA CLOSED SYSTEMWilli Bender, Berlin, Germany, assignor to Pintsch BamagAlttiengesellschaft Application March 1, 1952, Serial No. 274,465

Claims priority, application Germany March 9, 1951 9 Claims. (Cl.237--56) The invention relates to a method of, and means for,circulating n heat-transferring liquid in a closed system.

With known methods and arrangements for heating apparatus forevaporating, distilling-and chemical reacting purposes by means of anorganic heating medium, for example diphyl, which is a mixtureofdiphenyl oxide and diphenyl, flowing in a closed circuit, it has beenfound that the thermo-syphonic effect alone'is not sufiicient for a goodheat transfer and that it is necessary to pump the heating medium aroundthe closed circuit, the heating medium being evaporated and condensed ina closed heating-coil system known per se comprising, behind aheat-receiving portion of the heating-coil system, a separator whichretains liquid particles and from which the liquid phase is returned bya duct to the heat-receiving portion while the steam phase flows througha duct to a heat-consuming apparatus, for example an autoclave, and fromwhich the steam phase returns as condensate to the heat-receivingportion.

it is an object of the invention to-provide a method of, and means for,circulating a heat-transferring liquid in a closed system in which thecirculation is inherently improved without the necessity of providingmechanical means, such as a pump.

Other objects and advantages of the invention will become apparent tothose skilled in the art from the following detailed description of anembodiment of the invention when read in conjunction with theaccompanying drawing diagrammatically illustrating an embodiment of theinvention.

The invention is based-on the idea ofadding one or more gases, forexample hydrogen, helium, or nitrogen under pressure to the heatingmedium, for example diphyl, the pressure being chosen to correspondto'the desired temperature. The gaseous phase is partly dissolved by theliquid and is, on evaporation of the liquid, expelled again, whereby thecirculation of the heat-transferring medium is enhanced. Moreover, theenhanced circulation is still further improved by the alteration of thevolume of the gaseous phase in dependence on the temperature.

In the drawing, a heat receiving portion .1 (i. e. heat evolving means)of the heating-coil system is arranged in a combustion chamber, theorganic heating medium being heated and vaporized in the heat-receivingportion 1. Thecombustion chamber is heated by a combustible gas or oil GWhile compressed air .1. is added. The mixture of liquid and steamreaches a separator 2 in .Which the liquid phase is separatedfrom thesteam-gaseous phase. The liquid leaving the separator 2. flowsthrough-aduct 3 back into the portion 1. The mixture of vapor and gasleaving the separator 2 flows through a duct 4 .into an apparatus 5 (i.e. heat evolving means)-to be heated, for example an autoclave, the heatof'whichis fed to :a substance to be heated. The condensate, he. theliquid consisting of condensed vapor plus gas dissolved therein, leavingthe autoclave 5 is fed back through :a duct fi-into the heat-receivingportion 1.

To allow for the increase in volume of :the heating hired tates Patentmedium, which is due to the raised temperature, a receiver 7 is insertedinto the duct 6 for the-condensate. The action of gravity causes acirculation of the heating medium in the direction indicated by thearrows owing to the fact that in the falling duct the-condensate iscollected until it reaches a certain level. In any case, this level'lies above the uppermost winding of the coil of the heat-receivingportion 1, the circulation of the heating medium being additionallyenhanced by the decrease in volume of the heating medium, which takesplace in the autoclave due to the condensation of the fluid vapor, aswell as by the decrease in volume of the gaseous phase due todissolution of the gas in the fluid which now is in liquid state againand by the reduced pressure thus created in this part of thesystem.Thereby, the mixture of vapor and gas is sucked otf from theheat-receiving portion 1.

The receiver 7 (i. e. collecting means) consists of a helical tube; ithas to be arranged as high as possible above the heat-receiving portion'1, but below the auto clave 5. By this arrangement, a high level of thecondensate is obtained, which also enhances the circulation.Incidentally, the additional advantage is thereby obtained that theautoclave remains free of the condensate.

When the heated material has to be cooled as quickly as possible, thenthe duct 4 for the mixture of vapor and gashas to be short circuited tothe duct 6 for the condensate by a connecting duct 8, which may be acooled tube or else may be constructed as a cooling device. Thisshort-circuiting duct 3 need not be provided with a valve, because themixture of vapor and gas will always flow to that place at which a lowerpressure exists. in order that the autoclave 5 remains in fact switchedout of the circulation, it is necessary to ensure the condensation .inanother portion of the circulation system, for example between theautoclave 5 and the heat-receiving portion 1, in which case theshort-circuiting duct it has to be cooled. Instead of cooling the duct8, alternatively the receiver '7 or else the duct ,6 for the condensatemay be constructed as a cooling device.

For filling the circulation system, a storage container 9 is provided,at a higher level than that of the autoclave 5, the heating mediumflowing under its own Weight from the storage container 9 towards thecirculation system after valves 10 and .llhave been opened. Duringfilling, a vent valve 12 has to be open so that the air in thecirculation system can escape. The circulation system is filled with theheating medium until the latter reaches the vent valve 12, which is thenclosed. After the valve 11 has been also closed, the gaseous phase Wforexample hydrogen, helium, or nitrogenis added to the circulation systemthrough a duct 13, whereby the liquid level andthe pressure can beadjusted in a desired manner, the excess heating medium being pressedback into the storage container 9. After .the filling of the circulationsystem has been completed, the valve 10 is closed and, for the requiredoperation, the control valve 11 is opened fully or in part whereby tocontrol the speed with which the heating medium circulates.

For emptying the circulation system, the valve 11 is closed, the valve10 is opened and, by means of compressed air L fed through the duct 13,the heating medium is pressed back into the storage container 9. By thisarrangement the loss of heating medium may be minimized. The storagecontainer'9 is vented by means of a long tube 14 having a separator forthe liquid and being arranged above the roof.

It should be clearly understood that the accompanying drawings are givenby way of example only, many modifications, additions .and omissionsbeing possible without departing from the'spirit of this invention.

I claim:

1. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point of said circuit; and amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid and a circulationaccelerating low boiling point gas, said gas being insoluble in saidhigh boiling point fluid at the pressure and temperature prevailing insaid heat absorbing means and soluble in said fluid at the pressure andtemperature prevailing in said heat-evolving means, said heattransferring fluid in liquid state and with said gas substantiallydissolved therein being vaporized in said heat absorbing means wherebysaid gas is released, the thus created fluid vapor and gas mixtureflowing into said heat evolving means where said fluid vapor iscondensed and said gas again dissolved therein, said release anddissolution of said gas from and in said fluid resulting in increase ofpressure in said heat absorbing means and reduction of pressure in saidheat evolving means, respeclively, which in turn causes acceleration ofcirculation of said heat transferring fluid.

2. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point or said circuit; and amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid and a circulationaccelerating low boiling point gas, said gas being selected from thegroup consisting of hydrogen, helium, and nitrogen, said gas beinginsoluble in said hi h boiling point fluid at the pressure andtemperature prevailing in said heat absorbing means and soluble in saidfluid at the pressure and temperature prevailing in said heat-evolvingmeans, said heat transferring fluid in liquid state and with said gassubstantially dissolved therein being vaporized in said heat absorbingmeans whereby said gas is released, the thus created fluid vapor and gasmixture flowing into said heat evolving means where said fluid vapor iscondensed and said gas again dissolved therein, said release anddissolution of said gas from and in said fluid resulting in increase ofpressure in said heat absorbing means and reduction of pressure in saidheat evolving means, respectively, which in turn causes acceleration ofcirculation of said heat transferring fluid.

3. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point of said circuit; amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid and a circulationaccelerating low boiling point gas, said gas being insoluble in saidhigh boiling point fluid at the pressure and temperature prevailing insaid heat absorbing means and soluble in said fluid at the pressure andtemperature prevailing in said heat-evolving means; and storage meansfor said heat-transferring fluid connected to said conduit means betweensaid heat evolving means and said heat absorbing means, said heattransferring fluid in liquid state and with said gas substantiallydissolved therein being vaporized in said heat absorbin means wherebysaid gas is released, the thus created fluid vapor and gas mixtureflowing into said heat evolving means Where said fluid vapor iscondensed and said gas again dissolved therein, said release anddissolution of said gas from and in said fluid resulting in increase ofpressure in said heat absorbing means and reduction of pressure in saidheat evolving means, respectively, which in turn causes acceleration ofcirculation of said heat transferring fluid.

4. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point of said circuit; amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid and a circulationaccelerating low boiling point gas, said gas being insoluble in saidhigh boiling point fluid at the pressure and temperature prevailing insaid heat absorbing means and soluble in said fluid at the pressure andtemperature prevailing in said heatevolving means; storage means forsaid heat-transferring fluid connected to said conduit means betweensaid heat evolving means and said heat absorbing means and arranged on alevel higher than said heat evolving means; and valve means for closingand opening the connection between said storage means and said conduitmeans, said heat transferring fluid in liquid state and with said gassubstantially dissolved therein being vaporized in said heat absorbingmeans whereby said gas is released, the thus created fluid vapor and gasmixture flowing into said heat evolving means where said fluid vapor iscondensed and said gas again dissolved therein, said release anddissolution of said gas from and in said fluid resulting in increase ofpressure in said heat absorbing means and reduction of pressure in saidheat evolving means, respectively, which in turn causes acceleration ofcirculation of said heat transferring fluid.

5. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point of said circuit; amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid and a circulationaccelerating low boiling point gas, said gas being insoluble in saidhigh boiling point fluid at the pressure and temperature prevailing insaid heat absorbing means and soluble in said fluid at the pressure andtemperature prevailing in said heat-evolving means; and means connectedaround said heat absorbing means for separating and removing liquid fromsaid mixture leaving said heat absorbing means and for returning theliquid to the latter means, said heat transferring fluid in liquid stateand with said gas substantially dissolved therein being vaporized insaid heat absorbing means whereby said gas is released, the thus createdfluid vapor and gas mixture flowing into said heat evolving means wheresaid fluid vapor is condensed and said gas again dissolved therein, saidrelease and dissolution of said gas from and in said fluid resulting inincrease of pressure in said heat absorbing means and reduction ofpressure in said heat evolving means, respectively, which in turn causesacceleration of circulation of said heat transferring fluid.

6. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point of said circuit; amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid and a circulationaccelerating low boiling point gas, said gas being insoluble in saidhigh boiling point fluid at the pressure and temperature prevailing insaid heat absorbing means and soluble in said fluid at the pressure andtemperature prevailing in said heat-evolving means; and collecting meansin said conduit means between said heat evolving means and said heatabsorbing means for receiving condensate of said heat transferringliquid from said heat evolving means and for returning the con densateto said heat absorbing means, said heat transferring fluid in liquidstate and with said gas substantially dissolved therein being vaporizedin said heat aba conduit means forming a closed circuit havingvertically spaced lower and higher points; heat-absorbing means in saidcircuit at said lower point thereof; heat evolving means at said higherpoint of said circuit; a mixture being under pressure and filling saidconduit means and composed of a heat-transferring high boiling pointfluid and a circulation accelerating low boiling point gas, said gasbeing insoluble in said high boiling point fluid at the pressure andtemperature prevailing in said heat absorbing means and soluble in saidfluid at the pressure and temperature prevailing in said heat-evolvingmeans; storage means for said heat-transferring fluid connected to saidconduit means between said heat evolving means and said heat absorbingmeans and arranged on a level higher than said heat evolving means;valve means for closing and opening the connection between said storagemeans and said conduit means; and collecting means in said conduit meansbetween said heat evolving means and said heat absorbing means forreceiving condensate of said heat transferring liquid from said heatevolving means and for returning the condensate to said heat absorbingmeans, said heat transferring fluid in liquid state and with said gassubstantially dissolved therein being vaporized in said heat absorbingmeans whereby said gas is released, the thus created fluid vapor and gasmixture flowing into said heat evolving means where said fluid vapor iscondensed and said gas again dissolved therein, said release anddissolution of said gas from and in said fluid resulting in increase ofpressure in said heat absorbing means and reduction of pressure in saidheat evolving means, respectively, which in turn causes acceleration ofcirculation of said heat transferring fluid.

8. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point of said circuit; and amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid consisting of diphenyloxide and diphenyl, and a circulation accelerating low boiling pointgas, said gas being insoluble in said high boiling point fluid at thepressure and temperature prevailing in said heat absorbing means andsoluble in said fluid at the pressure and temperature prevailing in saidheat-evolving means, said heat transferring fluid in liquid state andwith said gas substantially dissolved therein being vaporized in saidheat absorbing means whereby said gas is released, the thus createdfluid vapor and gas mixture flowing into said heat evolving means wheresaid fluid vapor is condensed and said gas again dissolved therein, saidrelease and dissolution of said gas from and in said fluid resulting inincrease of pressure in said heat absorbing means and reduction ofpressure in said heat evolving means, respectively, which in turn causesacceleration of circulation of said heat transferring fluid.

9. A heating apparatus comprising, in combination, a conduit meansforming a closed circuit having vertically spaced lower and higherpoints; heat-absorbing means in said circuit at said lower pointthereof; heat evolving means at said higher point of said circuit; and amixture being under pressure and filling said conduit means and composedof a heat-transferring high boiling point fluid consisting of diphenyloxide and diphenyl, and a circulation accelerating low boiling pointgas, said gas being selected from the group consisting of hydrogen,helium, and nitrogen, said gas being insoluble in said high boilingpoint fluid at the pressure and temperature prevailing in said heatabsorbing means and soluble in said fluid at the pressure andtemperature prevailing in said heat-evolving means, said heattransferring fluid in liquid state and with said gas substantiallydissolved therein being vaporized in said heat absorbing means wherebysaid gas is released, the thus created fluid vapor and gas mixtureflowing into said heat evolving means where said fluid vapor iscondensed and said gas again dissolved therein, said release anddissolution of said gas from and in said fluid resulting in increase ofpressure in said heat absorbing means and reduction of pressure in saidheat evolving means, respectively, which in turn causes acceleration ofcirculation of said heat transferring fluid.

References Cited in the file of this patent UNITED STATES PATENTS1,087,274 Check et al Feb. 17, 1914 2,360,665 Fields Oct. 17, 19442,510,737 Buffington June 6, 1950 2,532,608 Dalin Dec. 5, 195.0

